The experiments in this project use innovative gene delivery techniques and a multipronged approach to assess the fundamental role of astrocyte activation in neurologic function in an intact mouse model of Alzheimer's disease (AD). Studies use adeno-associated virus vectors (AAV) bearing the astrocyte-specific promoter Gfa2 to target the protein phosphatase calcineurin (CN) and NFAT transcription factors in astrocytes of wild-type and APP/PS1 mice. AAV-Gfa2 vectors are bilaterally delivered to the hippocampus at different ages/disease stages and mice are assessed on different AD biomarkers. In Aim 1, cognitive status is assessed using the active avoidance task, while synaptic function is evaluated using hippocampal slice electrophysiology and Western blot measures of synaptic proteins. In Aim 2, hippocampal glutamate regulation is investigated using ceramic enzyme-based microelectrode arrays and measures of glutamate transporter levels. In Aim 3, levels of glial activation and neuroinflammation are determined with immunohistochemical (IHC) analyses and assessment of cytokine levels using Multiplex ELISAs. In Aim 4, IHC is used to determine the extent of A? deposition, while ELISAs are used to quantify levels of A?40 and A?42 in soluble and insoluble hippocampal tissue fractions, and Westerns used to assess BACE protein expression. AAV-Gfa2 vectors encode either potent inhibitors or activators of CN/NFAT signaling and therefore will determine the necessity and sufficiency of this astrocytic pathway in driving and/or maintaining neurologic dysfunction in AD mice. These studies provide a highly novel approach to the study of activated astrocytes and could have a major impact on the development of treatment strategies for AD and other neurodegenerative conditions.